1. Field of the Invention
The present invention concerns the field of fracture fixation and relates more particularly to an apparatus which is used in the external fixation of fractured bones.
2. Description of the Prior Art
A large number of external fixators are known which are connected to the bone fragments by sets of pins which are inserted into each of the bone fragments. The problem involved in putting this type of fixator into place is that of being able to return the bone fragments to the precise original position. Thus, fixators have already been proposed with which it is possible to orient the pins, and consequently the bone fragments. U.S. Pat. No. 5,160,335, for example, describes a fixator which includes two supports for bone pins which supports are separated by a telescopic bar. It is possible for each support to be pivoted in three orthonormal axes.
U.S. Pat. No. 5,397,322 discloses a reducing apparatus arranged between two clamps for gripping the pins which are inserted in each of the bone fragments. This reducing apparatus includes an adjustable circular sector which is equipped at each end with means for rotation and axial displacement of one of the gripping clamps. It thus permits a micrometric displacement of the bone fragments in all degrees of freedom, by means of axial displacements and angular rotations. The manipulations can thus be performed independently of one another in such a way as not to compromise a reduction result which has already been achieved. The teachings of U.S. Pat. No. 5,397,322 are incorporated herein by reference.
However, the design of these prior art devices makes it difficult for the practitioner to visualize the movement he will effect using one of the numerous screws or adjustment levers. In seeking to improve the relative positioning of the bone fragments, one runs the risk of disturbing the results which have already been obtained.